The present invention relates to detection of optical signals in particular with respect to phase and amplitude.
In high-speed optical telecommunication, the phase of the optical signal has become increasingly important as additional degree of freedom for transmitting information. A know concept is usually referred to as coherent detection.
In coherent detection, an optical receiver provides (time dependent) electrical signals thus allowing determining the time dependent course of the optical signal with respect to its amplitude and phase. The time dependent course of the phase contains the digital data content of the optical signal.
Coherent detection in optical fiber systems is outlined in the articles “Coherent detection in optical fiber systems”, by Ezra Ip, Alan Pak Tao Lau, Daniel J. F. Barros, Joseph M. Kahn, 21 Jan. 2008, Vol. 16, No. 2, OPTICS EXPRESS, p. 753 ff; or in “Phase- and Polarization-Diversity Coherent Optical Techniques”, by Leonid G. Kazovsky, JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL 7, NO. 2, FEBRUARY 1989, page 219 ff.